The present invention relates to a load-bearing vehicle roof of so-called sandwich construction, wherein the material layers included in the vehicle roof comprise polymeric material, laminate material and/or metal layers.
Furthermore, the invention relates to a method for manufacturing such a vehicle roof, wherein the method comprises laminating and/or compression moulding methods.
The material structure of the vehicle roof according to the invention comprises a core with high bearing resistance and low density, wherein the core on both sides is enclosed by layers with high strength. In this way, a rigid construction with high load-bearing capability and low weight, and good sound and heat insulating ability, is obtained. Furthermore, the vehicle roof according to the invention provides both the outer and inner roof before mounting onto a vehicle body takes place, for which reason no separate inner roof has to be post-mounted.
The present invention has its main application within the field of ground-based vehicles, such as passenger cars or commercial vehicles.
In conventional manufacturing of vehicle roofs of automotive sheet metal, different metal working operations, such as pressing, rolling, bending and welding, are usually utilized. Such conventional vehicle roofs are provided in one or several separate steps with possible sound insulating layers and different decorative layers on the side of the vehicle roof which will be facing towards the passenger compartment. As a rule, this takes place at the end of an assembly line for motor vehicles.
Conventional sheet metal roofs constitute an integrated, load-bearing part of the body of a vehicle and, with the presently utilized constructions, provide a great contribution to the strength and stiffness of the body and relatively good protection in a possible accident where, for example, a motor vehicle rolls or ends up resting on its roof. Something which might be perceived as a disadvantage with conventional sheet metal-based vehicle roofs is their relatively high weight.
Detachable roofs of for example plastic material, so-called hard-top roofs, are previously known. Roofs of this type, however, do not contribute to the stiffness of the vehicle body to any great extent, for which reason the body or the chassis has to be provided with additional reinforcements in order to increase the stiffness and the load-bearing capability.
Furthermore, so-called folding tops, i.e. upwardly and downwardly foldable roofs of different reinforced textile and/or plastic materials for use in for example convertible cars, are also long since known. Neither do such roofs contribute significantly to the stiffness of the vehicle and provide only an insignificant load-bearing capability, for which reason additional reinforcements are necessary.
Furthermore, vehicle roofs of thermosetting plastic composites with a sandwich structure are previously known. Such previously known vehicle roofs require that a separate inner roof is mounted after the outer roof has been mounted on the body, in a similar way as when sheet metal-based roofs are concerned.
Accordingly, the first object of the present invention is to provide a load-bearing vehicle roof which, already before being mounted onto a motor vehicle, provides both the inner and outer roof, and which after having been mounted constitutes a load-bearing, integrated part of the body of the vehicle.
In accordance with claim 1, this object is achieved by means of the load-bearing vehicle roof according to the invention comprising an outer cover layer, a core and an inner cover layer, which together form a load-bearing structure, and that thereby at least one insulating layer and/or one decorative layer intended to be visible from a passenger compartment within a motor vehicle is/are provided inside the inner cover layer, and that the insulating and/or decorative layers is/are provided as layers of the load-bearing vehicle roof before mounting onto said motor vehicle.
A second object of the present invention is to provide a method for manufacturing a load-bearing vehicle roof of the above-described type.
In accordance with claim 12, this object is achieved by means of the method according to the invention comprising preforming an outer cover layer and joining the preformed outer cover layer to a preformed core and applying an inner cover layer thereon in order to thereafter create a load-bearing structure by means of a consolidation, and that thereafter at least one insulating layer and/or at least one decorative layer intended to be visible from a passenger compartment within a motor vehicle is/are attached to the inner cover layer after the consolidation, and that the insulating and/or decorative layers are fixed to the inner cover layer before the load-bearing vehicle roof is mounted onto a vehicle body of the motor vehicle.